I enjoyed the game. The only bug I encountered occurred when I finished a round and the entities on the screen started to slow down. I must have quickly hit the space bar to return to the skill menu, because everything on the screen slowed down and remained that way until I entered another round and intentionally died.
The only issue I found occurs when there are too many entities on the screen. This caused some of the lasers to simply vanish and some of the asteroids to become invisible, but still harmful. I actually died to an invisible crystal because of this.
Otherwise, it is an excellent demo and I look forward to seeing the completed product.